A railroad turnout or switch is operable to move a pair of "switch rails" or "switch points" transversely into contact with adjacent main rails, so as to direct a train along either the main track or an adjacent siding track. Although the distance which the switch points move is quite small, the steel rail is quite heavy, and requires a large amount of force to shift the switch points as necessary.
Conventionally, switch points slide over bearings or bearing plates, supported by sleepers or ties. In order to insure smooth sliding of the switch point, this base plate is preferably well lubricated.
In order to eliminate the periodic application of lubricating fluid on the base plate, attempts have been made to provide a reduced friction surface on the base plate over which the switch points will slide. One example is disclosed in U.S. Pat. No. 4,890,804 to Teramoto et al., wherein a sprayed coated ceramic layer is formed on the base plate.
U.S. Pat. No. 4,105,175 to De Spiegeleer discloses a bearing plate with a self-lubricating sliding surface. More recently, U.S. Pat. No. 5,127,613 discloses an antifriction insert introduced on a base plate for supporting switch points. While the above-described devices improve the sliding of the switch point on the base plate, they still suffer several drawbacks. First, prior art switch point bearing surfaces are typically not easily attached or removed from the railroad track, thereby increasing the amount of time and effort required to install such devices at switches, and increasing the cost to install such devices.
In addition, most prior art devices are not adjustable so as to "fine tune" the switch point bearing device for the particular conditions and orientation of the ties and switch points adjacent the main rail. Thus, the wear plate can receive uneven wear from movement of the switch point and decrease the use for life of the wear plate.
Finally, prior art switch point movement assisting devices typically include complicated structure having numerous parts which are not easily replaceable or repairable.